Abstract Programs for the prevention of mother-to-child transmission of HIV (PMTCT) are a critical entry point for long-term HIV care. The benefits to both mother and infant are substantial and include reduced HIV transmission to the infant and improved maternal and infant survival. These impacts are more pronounced in cases of maternal CD4+ cell counts d 350 cells/uL, the threshold of eligibility for combination antiretroviral therapy (ART) in pregnant women in most resource- constrained settings. Thus, an important focus of PMTCT remains identification of ART-eligible mothers and initiation onto treatment. However, this is often a challenge in resource-constrained + settings. Lengthy turnaround of laboratory tests, including CD4 screening, is a major barrier that may prevent the timely initiation of ART, mitigating the potential public health benefits to HIV- infected women and their infants. + We propose an evaluation of point-of-care (POC) CD4 technology to address this operational challenge across four public PMTCT facilities in the Lusaka District of Zambia. The clinics will + offer POC CD4 testing to women who are newly diagnosed with HIV infection. All women will + immediately be given a routine or urgent referral to ART services dependent on their CD4 cell count. We will use other government sector clinics matched by size, HIV prevalence, ART services in MCH and presence of labour wards as contemporaneous controls, as well as each site as its own historic control. Outcomes will include: (1) proportion of women initiating ART + within 4 weeks of CD4 testing among those deemed eligible by local criteria, (2) proportion of women on ART for at least 4 weeks and for at least 12 weeks before delivery, (3) proportion of infants who are HIV-infected per DNA PCR at the 6 week visit, and (4) field performance of the + novel POC CD4 testing system. To our knowledge, this operations research study will be the + first to look at the impact of POC CD4 testing on clinical outcomes. 2